This document explains how to use Media Gateway Control Protocol (MGCP)
between a Cisco IOS® Gateway (for example, VG200, 2600, 3600, IAD2400) and a
Cisco CallManager 3.x Media Convergence Server (MCS). It covers the
configuration of one T1 channel associated signaling (CAS) connection to the
Public Switched Telephone Network (PSTN). The remote site is an H.323 gateway.
VoIP connectivity to Cisco 7960 IP Phones are also shown. When this
configuration is complete, it will be possible to make calls between all of the
phones used in this configuration. In addition, it will be possible to route
calls over the PSTN from any of the phones used in this configuration.

This document assumes that the reader is already familiar with how to
configure Cisco IP Phones in Cisco CallManager. It also assumes that there is
at least one IP Phone already active on the Cisco CallManager server.

Symptoms:

This is a list of possible symptoms you might encounter with MGCP
gateways and what to check for:

This configuration was tested with Cisco CallManager 3.3(2) and a Cisco
IOS Software Release 12.2(13) image. The screen shots and IOS configuration
were captured using the software, hardware and other equipment here.

The information in this document was created from the devices in a
specific lab environment. All of the devices used in this document started with
a cleared (default) configuration. If your network is live, make sure that you
understand the potential impact of any command.

Note: Cisco IOS Software Release 12.2(11)T or later is recommended based on
the ccm-manager command enhancements. The
ccm-manager command requires Cisco IOS Software
Release 12.1(5)XM or later on all Cisco routers (2600, 3600) and the VG200.

Cisco 2600 and 3600 routers support MGCP if they are running Cisco IOS
Software Release 12.1(3)T or later. The release and version that you require is
based on the features that you need to enable. The Cisco CallManager server
must run version 3.0(5)a or later. The router configuration is the same for all
types of routers. The Cisco CallManager configuration is also the same for all
types of routers.

Cisco IOS Software Release 12.1(5)XM1 and later supports the VG200. The
release and version that you require is based on the features that you need to
enable. Although the VG200 is supported in earlier releases of Cisco
CallManager, version 3.0(5)a or later is recommended.

This document guides you through a simple Media Gateway Control
Protocol (MGCP) configuration. Only the minimum commands are required to build
a working configuration for a router with one T1.

Note: The configuration in this document works for a Cisco VG200, 2600, or
3600 series router that runs Cisco IOS® Software Release 12.1(5)T or later. For
other IOS MGCP gateways, check the IOS documentation for supported versions.

Note: In some Cisco IOS Software Releases, the application
MGCPAPP command is case sensitive. Unless you know
that your version is not case sensitive, always enter this command in upper
case. You can check whether your version is case sensitive after you configure
this command when you look at the output of the show
running-config command. Cisco IOS Software Release 12.1(5)T is
not case sensitive.

Make certain that the voice ports are enabled.

Note: The shutdown and no
shutdown commands affect both ports on a voice interface card
(VIC). It is only necessary to enter the command on one of these ports.

Enable IP connectivity.

If any of the VoIP devices that the Cisco 2600 communicates with
are located on different subnets/VLANS, enable IP routing and create a gateway
of last resort (default network). This step explains how to perform both tasks.

Note: On the Cisco IOS Gateways (which are essentially routers with
voice interfaces), you can configure a routing protocol instead of static
routes. The important issue is to ensure IP connectivity between VoIP devices.

Note: For VG200, when you enable IP routing, the ip
routing command does not appear in the configuration because it
is normally on by default and default commands do not usually appear in a Cisco
router configuration. The VG200 Cisco IOS images override the default behavior
of having IP routing enabled by hard coding the no ip
routing command into the initial configuration. The initial
configuration is created when the image is booted on a platform that has had
its configuration cleared by the write erase command
or when it is booted up a VG200 that has never been configured.

The ip route 0.0.0.0 0.0.0.0
<ip_address_of_gateway> command causes the VG200 to install
a gateway of last resort into its routing table. The show ip
route command confirms this. In the example below, the gateway's
IP address is 172.16.13.35.

Note: The ip classless command is also
required in order for this gateway of last resort to be effective. The
ip classless command is enabled by default. It is
one of the few Cisco IOS default commands that appears in a configuration when
it is enabled and also appears in the "no" form when it is disabled. If your
configuration has the line no ip classless, enter
the ip classless command to enable ip
classless.

Caution: All dial plan related configuration elements are controlled by
Cisco CallManager and should not be configured in the MGCP gateway for
MGCP-managed endpoints (those with the application
MGCPAPP command in their dial-peer statement). You
should not configure any of these functions:

Under Dial Peers:

destination-pattern

session-target

Under Voice Ports:

connection { plar | tie line | trunk }

The Cisco 2600 is now ready to communicate with the Cisco
CallManager server. It periodically sends out messages in an attempt to
establish a connection. When the Cisco CallManager server configuration is
complete, the connection should automatically establish itself. You should not
have to make any further changes on the Cisco 2600.

Note: It is a good practice to reset the gateway ports after you
complete the configuration, as shown in this example.

In this task, a Cisco 2611-based MGCP gateway is created. The material
in this section also applies to other Cisco IOS MGCP routers. The only
difference is the platform that you select in step 3.

Select Device > Gateway to use
the Device Wizard to create an MGCP gateway.

Click Add a New
Gateway.

Select the Gateway Type (in this case, it is Cisco26xx).

Note: In the Device Protocol field, notice that the only option is "Not
Required for MGCP." This means that no protocol needs to be selected if the
gateway is an MGCP gateway.

Note: If you are using another Cisco IOS router, select the appropriate
gateway type (such as Cisco 26xx or 36xx). This is the only step that is
different. The remaining tasks apply to the Cisco VG200 as well as the Cisco
2600 or 3600 Series Routers.

Click Next.

For the MGCP Domain Name, use the actual host name that you
assigned to the Cisco 2600 (in this case, 2611-4) and specify the carrier
module that the 2600 has installed (in this case, it is an NM-HDV).

Note: The voice carrier modules for the IAD2400 are different than
those of the Cisco VG200, 2600, and 3600.

Note: The MGCP Domain Name parameter is case sensitive.

Click Insert.

Note: If the Cisco IOS router/gateway is configured with a domain name
ip domain-name word, the MGCP Domain Name field
needs to include it. For example,
2600.company.com.

If you have already completed the tasks to configure the Cisco 2600, it
has been sending MGCP messages to the Cisco CallManager server attempting to
establish an MGCP relationship. If Tasks 1 through 4 are a success, the Cisco
CallManager server and the Cisco 2600 are now ready to route local calls
between any IP phones registered to the Cisco CallManager server and PSTN.

You should also be able to dial the IP Phones that are configured as
well as call the analog phones from the IP Phones. Try to complete calls to and
from all of the phones in your configuration.

Note: If some of your phones cannot place or receive calls, look at your
partition, Calling Search Space (CSS), device pool, and location
configurations. You may have a configuration that does not allow all local
phones to call each other. If this is the case, temporarily place one IP Phone
and one analog phone (FXS port) in the same partition, device pool, location,
and CSS and try the test again.

Note: If you encounter issues with the Cisco IOS gateway registration or
gateway operation, try to reset the gateway voice ports, as shown in this
example.

router(config)#voice-port 1/0:1
router(config-voiceport)#shutdown
Both ports are out of service
router(config-voiceport)#no shutdown

You should now be able to route calls over the PSTN from any phone on
the system when you dial 9, and then dial the called number after the dial tone
comes back. In the traces below, a call is made from an IP Phone and captures
the MGCP packet traces.